Cultured human cells will be used to evaluate in vitro pesticide toxicity. Measurements of toxicity based on changes in cellular biochemical processes will be compared to effects on cell growth. Effects of several pesticides including aldrin, dieldrin, parathion, pyrethrin compounds, pentachloronitrobenzene (PCNB), chlorobenzilate (ASA), and PCB isomers on biosynthesis of macromolecules in HeLa cells and human foreskin fibroblasts (HF-cells) will be monitored by measuring cellular utilization of radio-labeled amino acids, uridine, and thymidine. Studies will be conducted to optimize culture conditions for measuring biochemical parameters. Other investigations will be conducted to determine mechanisms by which toxic agents inhibit biosynthesis activities and lead to inhibition of cell growth. Included will be studies to determine pesticide effects on cyclic nucleotide levels, ATP levels and production, and on membrane transport phenomena. Results will provide basic information required for the development of an accurate-predictive cell culture screen for pesticides. BIBLIOGRAPHIC REFERENCE: Aldrin Toxicity in Mammalian Cells. DeVore, D.P., Sheridan, M.A., Pitman, J.S., and Hutson, T.B., (Abstract) The Pharmacologist, 18(2): 720, 1976.